The field of network security has become increasingly important in today's society. The Internet has enabled interconnection of different computer networks all over the world. It has provided a medium for users to access a vast amount of information resources and services. For example, the World Wide Web allows end users to access documents in the form of web pages over the Internet by simply requesting access to a valid network address or Uniform Resource Locator (URL) (e.g., network address that may include a protocol, a hostname, and a path to the filename). In another example, end users may exchange files with other end users or servers across the Internet. The wide-ranging security threats accompanying these and other uses of the Internet, however, present significant obstacles to individual users and organizations to maintain secure computer systems and to protect confidential information.
Many legitimate and useful techniques used in Internet communications are often exploited for malicious purposes. For example, URL redirection is a technique used to make web pages available under more than one URL. While URL redirection has several beneficial uses, many deceptive Internet tactics, such as web-based phishing, drive-by-downloads and other social engineering attacks, employ URL redirection techniques to redirect unsuspecting users to malicious websites. Some malicious websites may be designed to deceive users into downloading seemingly legitimate software that is actually some form of malware. Other malicious websites may be designed to trick users into providing personal or otherwise confidential information. As these tactics evolve, security professionals need to develop innovative tools to combat such tactics that seek to infect computer systems with malware and to obtain confidential information from end users.